


A Mysterious Encounter

by myheartismadeofstars



Category: Undertale (Video Game)
Genre: Gen
Language: English
Status: Completed
Published: 2016-03-08
Updated: 2016-03-08
Packaged: 2018-05-25 13:10:43
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,796
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6196336
Author URL: https://archiveofourown.org/users/myheartismadeofstars/pseuds/myheartismadeofstars
Summary: <blockquote class="userstuff">
              <p>Ten years after the Barrier was broken, Frisk takes Sans back into the Underground, and things get a little bit strange.</p>
            </blockquote>





	A Mysterious Encounter

“You promised!”

“i didn’t promise you anything. you know how i hate promises.” Sans told Frisk dismissively. The last promise he had made was to Toriel and that was over a decade ago.

“Come on, Sans! We’ll go for a hike and then we’ll go out for dinner when we get back! I’ll even _pay_!” She begged.

“kiddo, if you thought telling me you wanted to go hiking was going to convince me, then our ten year friendship was wasted.” Sans said, rolling onto his front, regretting ever giving her the key to his room, even though she had been using it for years at this point. 

Frisk groaned and grabbed Sans’ foot and started tugging on him to drag him off his mattress. “Get up, Lazybones.” She demanded. “You’re coming with me.”

* * *

 

Why did Frisk always win? Sans wondered as he hiked after the girl. Sure, he could use a shortcut to make it to the top, but Frisk would be mad...and it wasn’t worth it. 

Mt Ebott looked very different. Sans had avoided it like the plague for ten years and now, almost a decade to the day he left, he was following Frisk back there. The mountain had proper trails now (a nice touch) and it seemed like someone (Asgore maybe?) had planted “wildflowers” along them to make it look inviting. It seemed like a strange thing to do.

The hike was long and while Frisk had talked about eating, she seemed to forget about lunch once they reached the entrance to the Underground. 

“where are you taking me, kid?” Sans asked, hands in his pockets. He was tired from the hike, he wanted to rest. “I was thinking about Waterfall. You know how I love it there.” 

Frisk did indeed love Waterfall. She loved the Echo Flowers and their eternal whispering, she loved the shiny stones on the ceiling...she even had confessed to liking the somber and solemn feeling of the area. 

Honestly, Sans was feeling pretty nostalgic once they made it from Hotland into Waterfall. Frisk even slowed down to walk beside him, only leaving to talk to an Echo Flower or something. 

“This place is as beautiful as ever.” She sighed, putting her arm around his shoulders. Sans hummed in agreement. “we gonna head all the way to snowdin?” He asked.

“Yep! That’s the plan!” Frisk grinned happily. 

The conversations were simple and casual, even if Sans only half payed attention. Neither felt the need to keep talking at all times but when they did they joked and laughed easily. 

The two were passing through a hallway when Frisk abruptly stopped.

“kid?” Sans asked, stopping to look at what had caught her eye. Frisk stood right in front of a tall grey door in the wall. 

“Hey, Sans? Was this door always here?” She asked confused, taking a step towards the door.

“nope. never seen it before.” Sans didn’t trust it either, and moved to Frisk’s side.

By the time Sans reached her, Frisk’s hand was on the doorknob. “Frisk...” Sans said seriously. “You shouldn’t go in there. I don’t know where it leads.”

“Calm down, Sans. What is the worst thing that could happen?” She asked.

“You could let something out, that isn’t supposed to be let out.” Sans said, eyeing up the door suspiciously.

“It’s a _door_ , Sans. Not Pandora’s Box.” She closed the almost foot of distance between them and kissed the top of his skull. “I’ll just go in for a second.” She promised.

Sans didn’t relax, but he knew Little Miss Determined would do it anyway, so he let her. Frisk opened the door, but Sans couldn’t see anything but a grey pathway beyond it. She crossed the threshold and closed the door behind her, at which point the door vanished!

“Kid!” Sans felt panicked, hitting the wall where the door had been. “Kiddo! Come on, Frisk! Let’s keep going!!” He knew they should have left the damn door alone! It wasn’t normal, it wasn’t right...it wasn’t even logical, and it terrified him.

Sans tried for what his watch told him was several minutes to use his magic to break down the wall...but with his low ATK and inability to do more than 1 point of damage...he barely scratched the surface. He even tried to summon his Blasters...but for some reason he couldn’t access them.

Something here was very wrong...and Toriel was going to kill him if he went back without Frisk. Sans sat down on the opposite wall, feeling afraid for Frisk...and completely hopeless.

* * *

 

Frisk could hear someone calling her name...was it Sans? No. It was too far away to be Sans... She pressed forward. At the end of the corridor stood a monster Frisk didn’t recognize. Frisk felt her chest flutter and she was instantly thrown into a battle, her SOUL coming out to take the monster’s hits. Something about him seemed...familiar.

" F̴̧̬̞̺͍̱̬͚͙̰̩̲̘͉̬̞̯͕̟̫͘͟Ŗ̮̤̫̝͙̗̝̰̩̖͇̦̬̺͠͝͠I͞͠҉̡͍͍̲̖̙͈̼͚̜̹̬͜Ś̰̻͕̬̱̹̹̲̳͘K̴̶̞͔̮̙͇̱̤͔̯̰̰̻͎͘͜͟ͅ,̢̝͕͔̝̦̺́ ͏͏͍̩͚̣̰͇͎͈͕̗P̶̧̧̛̤͚̥͓̬̠̝̱̜̭̤̥͜ͅL̸̨͚͚͕͎̲̣̱̜̱͔͖̝̖̭͇̹̥̺̕̕͜E̴͚̞̣͔̜͘Á̴̲̭̬̰̲̦̯̦̻͔̝̲͇͜͟Ş̸̹͍̹̣̠̱̳͚̟͓̬̹͘̕È̘̰͔̳̤̜̣̝͖̳̕͢ͅ.̛́͜҉̹͓̝͈̟̳̝̩̥̱͍̦̬̗̬̳̞̫͘ ͞͏͍̙̲̥̤̟̰̬Y̴̨̘̹̜͓̳̮̯̺̣̲͈͍̬̯O̶̧͙͔̦̪̝̩̞͍͇̮͖̱̖̙̩̮͉̣̞͢͢Ư̹̫̯̰̖̫͔̦͓̳͎͖̹̣͘͝͠͠ͅ ̸̼͕͎̱̭̜͓͇̥͎̺̫͉̻̘̺̙͞M̲̠̭̖̀̕Ų̧̻͉̹̟̥͉̰̯̟͇̲͡S̵̵̗̰̗͈͉͉̼̟̩̬͔̤̯̱͔͚̜͘͝T͏̸̹̤͎̻̫͕͇̪̣̮̫̗̱̱̖̫̮̮̀ ̷͖͙̦͎̫̮̩̰̯͎́͡͠Ḩ̵̣̳̠̝̠̦̮͍͖̟͙͜E͏̴̡̤̦̦̣͉͇̥̳͉͢͝Ļ̙͚͙̯̖̼̻̬̼̖̰̝̼̩͡P̷̡̥̥͈̙͉̞͈̩͠ ̴̨̻̜͍͎̲̬͍͎̟̫̼ͅͅͅM̸̳̠̙͕͔̘̖̹̺̹̩͍͟͝Ę̶̞̜͖͉̱̰̲̠͓̠͔͢͜.̷̷͙̖̖̰͖͉̬̙̼͎̜͇͔̬̺̞͕̟̕͘͢ ” 

 

The figure said. His voice was...haunting, like something from a nightmare, and Frisk could not understand his strange speech. Was it a different language? Or just so garbled it was unintelligible? “ D̸̼͚̞͚̠͙̫̝̜̥͉̤̳́ͅO̴̵̗̩̻̝͝͠͝ ̲̱̥̞́̀̀́́N̨̛͓̤͓͔̺̗̝̕Ơ҉̶̱̱̰͚̬͈̞̤͇̙̥̲͈̻͚T̢̨̝̹̹̪͉́͢ ̸̧͖̭̞͍̻̱̲̮̙̝̀̕B̴̫̰̯̫̘͇̬͖̬͚̖͞Ę͢͡͏͙̖̭̳͉ ̸̸̖̟͖͓̦̲̲͕̦̖̺̦͙̲̹͈̰̗͜͢A̴̧͉͉̳̩̟̤̤̻̫F̴̧̛̯̦̣̙̣̣͕͜͠R̡̀͏̦͖̪̠̰̣͇͚̳͈͙͍̥̪̯ͅA͚̰̪͓̳̪̪͎͘͡Ì̶̧̹̼̩̜̪͍̤̗̫̙͍̖̬͔̥̣̥͚̕͜ͅD̰͍͓̗̩͔̕̕͡ ”

 

He summoned what looked like a giant gun in the shape of a skull. It made Frisk’s blood run cold. And it looked familiar somehow too... She clutched the old heart shaped locket that she had worn for years. She hoped it would be enough to protect her. She hoped her determination would be enough. The skull opened it’s mouth and blasted Frisk head on...no. Not Frisk. Her _battle interface_! Almost all of her interface was destroyed by the blast, leaving only her Bullet Board and SOUL intact. 

Oh. She could not ACT, she could not SPARE him, she could not use items...however, it didn’t look like she could lose health either... What was going on?

“ P̴̵̷̞̻̰͙͍̯̗͔͚̳̺̀͟L̛̜̗̳̫̰̀E̢͎̠̹̟͉͕̱̦̭̠̗̩͘͞A̸҉̩̤̜̬̬̬̻͚̹͎̩̱̪̜̙͈ͅS̶̵̤̫͇̱̗̼̹̥̦̟̜͙̮͉͎̮̣͘͞ͅÉ̵͙͚̜͓̤̹̘͖͈͈̝̻̰̝̥̠͚͝,̵̨͉͓͖̖̣̰̩̘͓̱͍̭ ̠͎͍̣͚͙̝̭̫͡M̧͘҉͓͖̝̙̙͖͍̭̦̫̲Y͟҉̕͏͍̫̫̞̳̮̣ͅ ͏̮̻͚̮͇̩́C͠҉̛͏͓̟̮̖̦̞̘̻̭̝͖̙̖̺̺͎H̷̨͎̦̹̬̻̀Í̢͎̹̗̮̮̱̀͠L̶̴̳͔̼̳̗̼͇̟̱͈̹̹͈͍͓͇͢D҉̢͉͔͚̠͚̝̼̗͙̲̲̮̟̦͎͟.̸̢̛̞̺̼̗̘̺̦̯͕̮̫̹̜̫̪́ͅ ̫̜͖͎̝̰̟̪̗̤̀́͞͠E̪̻̬͖͇̜̼̦̠͢͝͡͡ͅṈ̨̡̬̘̭́͜D͉͖̠̯͈̪̪̕͜Ú̵̷̴̧̙̻̹̖̹͖̘R̶̨̘͓͍̞̞̟̗͍̗͍͔̰͈͖͘͡Ȩ̷̰͔̝̥̦̖̜̙̞͕̫͖̀͞.̶̷̯̩̘̝̻̖̹͔͉̼̗̪͇̮̩͎̳͉́ͅ ̶̨̩̜͕̼̜̺͉̮̝̬̜̕͢Y҉͏̙̪̯̘̼̹͙̬͍̲͙̖͕̖͙ͅͅO͝҉̵̛͏̭̯̫̼̤͇̙͕̟͍̭͍͍̘̥̝ͅÙ̵̮̳͓͎̲͍͈̰̪̝̼̲̞̗͟ͅ ̶̷̼̖̜͖͈̲̼̜̪̟̰̝̠̰͓̕͢M̴̶̵̧̯̖̻͙̬͓̱̘͍̥̗̯͕U̧̳͓͉̬͚͇͚͕͔̫̜̩̠͙̻̙̹̰̗S͎͓̭͉̜̼̖̦͕̦͓͜͢͜͞͠Ţ͈̖̜̱̫̪͙̦̜̙̹̼͟ͅ!̶̀̕͢҉͓̟̣̼̘ ”

 

 The man said before launching into an attack. Her SOUL turned dark blue and was forced to submit to gravity, just like when she would fight with Papyrus. However...the attacks were much more erratic than Papyrus’ were. Sometimes they would come from the _wrong wall_  and Frisk wouldn’t even need to jump to evade them. The fight picked up speed and he seemed to gain better understanding of the blue SOUL, occasionally slamming Frisk’s poor SOUL into walls. 

The monster changed his attack halfway, Frisk’s SOUL abruptly changed back to red and the huge guns came out and attacked her from all sides “ I̵̧͏̩̘̭̞̟̫̼̱̺̺̱̬̻̫̦͢ ̵̸̞̳͖͕͓̺̳͓̺̮͎̮͢ͅͅḾ̪͚͚͈̞̤̦͙͙͖͉͖͝Ṷ̴̶̵̭̪̦̫͖̙̮̭̣̙̫̕S̢͖̭̫͡ͅT̡̙̖͙̯̦͙͕̻͙̟̩͉̘ ҉̬͈̙̗̫̮̤͙͙Ȩ̵̴̧͍̘̫̝͚̮̠̪̲̥͈̪͚̤̻X̷̷̵̥͉̜̳̞̱̜̝̝͚͓̦̮̹̜̖́I̸͖̩͉͞ͅS̢̳͖̙̬̖͙̠̘̕͡͞T̛͔̦̠̜̹̀́ ̴̮̺̮̱̘͍͈̩̯̙̥̲̰̜͢O̷̴̧̤̠̺̮̟͜Ņ̶̟̖̜̦̞̥̞̟̩̣̺̣̞ͅĆ̖͕̜͙̘̞̘̣̯̖̰̻͢͝È͟͏̹̭̭͙͍̤͉͈͚̮̹͖̪͕ͅ ̷̧̧̭̻̮̥͎̭̭͙̖͈̲̝̜͎̠̗̘͘͡ͅM̶̢͕̥̗̮̻̥͈̳͚͖̥̕O̶̱̙̳͙̣͕̭̪̭͉͘͜ͅR̡̢͔̗̯̯͕̲̲̫̯͇͉̀Ę̳͓͎͈̣̳̥̮̯̳̱̤͍̜̥̕!̵͘҉͖̗̦̤̣̯̲̤͈̬̺̜͈̱̗[  
](https://www.tumblr.com/edit/I%20MUST%20EXIST%20ONCE%20MORE!)” 

The monster’s voice cried out before the first blast hit Frisk’s SOUL.

Repeatedly throughout the encounter the strange monster would drastically change his tactics. Sometimes his attacks would last only seconds before switching, others seemed to drag on for hours before he ‘ended’ his attack. 

Frisk felt like this encounter had gone on for years. Like her entire life she had been in this tiny room dodging and enduring the attacks of this mysterious, vaguely skeletal monster. She was starting to forget why she had come here...

Finally the onslaught ended abruptly. Frisk was utterly worn out by it, and collapsed, breathing heavily. The monster came to her side and knelt. “THANK YOU, FRISK.” His voice was deep, and not as garbled as it had been before, but strong and clear. It had a soft accent. That _was_  another language he was speaking earlier. 

The tall monster gently picked Frisk up (not difficult, considering her size and weight) and let her rest her head on his shoulder. 

* * *

 

Sans heard a noise and looked up to see that the door was back. He jumped to his feet, ready to...what? Attack? He was too tired. Hug Frisk? Maybe...if it was her.

He saw a monster exit with Frisk in his arms. “Frisk!” He said, crossing to the other side of the hall. “Frisk, kiddo, speak to me..” He begged cursing his short height. He couldn’t see her properly.

“SHE IS RESTING.” The monster said. Sans thought the voice was familiar, and he looked up, staring at him in blank confusion for a moment. Then it hit him.

“dad?” 

“HELLO, SANS.” Doctor Gaster smiled at his son. 

“arentcha supposed to be dead?” Sans asked, gesturing for his father to put Frisk down so he could look her over. The doctor did as his son asked. Frisk looked a bit bruised, and very tired...but otherwise unharmed.

“NOT DEAD, BUT IN BAD SHAPE.” He explained. 

“you attacked frisk.” Sans accused, judging by her condition. Frisk had been in that room for three hours, no wonder she was tired.

“I DID. BUT I NEEDED TO USE HER DETERMINATION TO DRAW MYSELF BACK INTO THE TIMELINE! I WOULD HAVE DONE SO EARLIER BUT SHE WAS TOO YOUNG, HER SOUL TOO WEAK. SHE WOULD NOT HAVE SURVIVED WHEN SHE FIRST CAME. BESIDES, LIKE YOU SON, I NEEDED TO KNOW WHAT KIND OF PERSON SHE WAS.”

Sans said nothing. It was true. It had taken him two and a half years to accept that Frisk was what she said she was. He had been suspicious of her, worried about her getting bored and resetting them all again. His father probably didn’t want to live in a timeline where Frisk was cruel or dangerous. He didn’t like that she had been attacked, but...clearly an effort was made to make sure she didn’t die. Sans pressed his lip-less mouth to Frisk’s head, what she called a ‘skeleton kiss’.

“SANS, SHE IS DEHYDRATED. PLEASE GET HER WATER.” Doctor Gaster instructed. Sans straightened up. “there’s a water cooler in hotland, and i know a shortcut.” He turned to walk, apparently into the wall, but soon he was back with the cold water for Frisk.

Pouring the water slowly into Frisk’s mouth revived her. She coughed and sat up. She looked at Sans and a look of confusion crossed her face until she seemed to recognize him. “Sans!” She said, holding out her arms to hug him. “I was beginning to think I wouldn’t see you again.” Sans hugged Frisk tightly. “yeah, me too, friskie.” He said, trying not to cry when he thought about it. He didn’t want to lose her, not after all this time.

“COME, YOU TWO. I BELIEVE IT IS TIME FOR US TO GO HOME.”  Gaster said. “I WANT TO SEE THE SURFACE.”

Sans let go of Frisk and helped her to her feet. He didn’t let go of her hand. “sure thing, old man. i know a shortcut.” he smirked at his father.

“Let’s go, you dope.” Frisk said, teasing.

“yeah, your mother is going to kill me...”

And home they went.

**Author's Note:**

> 1\. Gaster's speech was originally in proper Wingdings, but nothing supports his Wingdings, APPARENTLY  
> 2\. He talks in all caps in his Wingdings so I carried it over into his normal text. So he's kinda like Papyrus. Except Gaster's caps feel more like a strong and clear voice than loud and exuberant like Papyrus. (That said, Gaster can ham it up as much as Papyrus can, you just can't really see it here)


End file.
